CLAS physics database search results Measurement E19M6 E89-004 R. A. Schumacher 2005 cos(theta) Cz Data errors dimensionless dimensionless dimensionless -0.7 0.171 0.612 -0.4 0.475 0.239 -0.1 0.681 0.156 0.2 0.866 0.138 0.5 0.632 0.135 0.8 0.458 0.22